Investigation of the applicability of silica-graphene hybrid materials as stationary phases for capillary liquid chromatography.

Graphene and graphene-derived substances are cutting-edge materials receiving increasing attention in the analytical chemistry field. Graphene oxide sheets bonded to amino silica particles functionalized with octadecyl (C18) groups and endcapped, also known as SiGO-C18ec, have been successfully employed as extraction phases and in analytical columns associated with conventional liquid chromatography (LC). In this work, SiGO-C18ec particles of 3, 5, and 10 µm nominal id were employed to pack capillary LC columns (100 mm long x 0.3 mm id), and their performance in the gradient mode was evaluated and compared. A 3 µm C18 capillary LC column (50 x 0.3 mm) was used as a reference column. Eight analytes having different polarities and topological surface areas were selected as a probe in this study: carbofuran clomazone, hexazinone, carbamazepine, citalopram, clomipramine, desipramine, and ochratoxin A. Studies about orthogonality were performed to investigate the orthogonality between the SiGO-C18ec and C18 phases. Among the SiGO-C18ec phases investigated, the column packed with 5 µm SiGO-C18ec particles presented the best peak capacity (29) in 15 min. Additionally, the performance of the columns packed with 5 µm SiGO-C18ec particles overcame the performance of the C18 columns used. Significant orthogonality was found between C18 and SiGO-C18ec packed columns; however, no significant differences were found between columns packed with SiGO-C18ec particles of different diameters.